gilbert



Nov. 26, 1.957

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INVENTOR EvERl-:TT GILBERT BY .n .E a7 ATTORNEY NGE Re. 24,397 Reissued Nov. 26, 1957 f ICC PROCESS FOR PREPARING DODECACHLORO- TETRAHYDRO-4,7-IVIETHANOINDENE Everett E. Gilbert, Morris Township, Morris County, N. J., assignor to Allied Chemical & Dye Corporation, New York, N. Y., a corporation of New York Original No. 2,702,305, dated February 15, 1955, Serial No. 219,739, April 6, 1951. Application for reissue August 19, 1957, Serial No. 679,116

3 Claims. (Cl. 260--648) Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specilication; matter printed in italics indicates the additions made by reissue.

This invention relates to a new method for preparing [dodecachhlorotetrahydro-4,7methanoindene] a dimer of hexachlorocyclopentadiene by the reaction of phosphorus pentachloride with [decachlorotetrahydro-4,7 methanoindene-one] the ketonic, hydrolyzed reaction product of hexachlorocyclopentadiene and sulfur trioxide, having the empirical formula C1aCl1oO.

The hexachlorocyclopentadiene dimer of my invention has been prepared in the past by the condensation of hexachlorocyclopentadiene with aluminum chloride as described in I. Am. Chem. Soc. 7l, page 954, March 1949, in the description of which process no structure was assigned to the hexachlorocyclopentadiene dimer.

I have now discovered the new process described below for preparing this hexachlorocyclopentadiene dimer [dodecachlorotetrahydro 4,7 methanoindenel This dimer compound is useful as an intermediate in carrying out chemical reactions and as an insecticide.

The [decachlorotetrahydro-4,7methanoindeneone] ketonic CmClloO compound which forms the starting material for my new reaction may be prepared, for example, as described in my copending application with Silvio L. Giolito, Serial No. 196,123, filed November 17, 1950, now U. S. Patent 2,616,928 by condensing two molecules of hexachlorocyclopentadiene with the aid of sulfur trioxide to form a hexachlorocyclopentadiene-SO3 reaction product and hydrolyzing the resulting reaction product to the ketone. It [is believed to be the 2,3,3a,4,5,6,7,7a,8,8 decachloro-3a,4,7,7a-tetrahydro-4,7-methanoindene-l-one illustrated below, and] usually exists in the form of a hydrate in a wide range of degrees of hydration.

The reaction as carried out according to my invention proceeds as follows:

chlorotetrahydro-4,7methanoindene] the hexachlorocyclopentadiene dimer of my invention. The dotted line A illustrates the spectrogram of the dimer as prepared according to the process of myv invention; the solid line B illustrates the spectrogram of the dimer resulting as the reaction product of hexachlorocyclopentadiene with aluminum chloride. -These spectrograms are substantially identical. Solid line C is the spectrogram of carbon disulfide used as solvent in preparing thespectrograms.

In carrying'out'the process of my invention, [deca- Chlorotetrahydro 4,7 methanoindeneone] the ketonic CmClzoO compound, preferably in substantially anhydrous form or in as low a state of hydration as practicable, is reacted with phosphorus pentachloride'to clect the replacement of the ketone group with chlorine, for example by mixing the reactants and heating the mixture. The resulting oily reaction productis then cooled and drowned in water,y whereupon solid hexachlorocyclopentadiene dimer crystallizes and may be recovered as by filtration and, if desired, washed with a liquid such as methanol which is a solvent for the [decachlorotetrahydro-4,7meth anoindeneone] ketonic CloClwO compound, but a nonsolvent for the reaction product, 'to dissolve any unreacted [decachlorotetrahydro 4,7-methanoindeneone] ketonic CioClioO compound which may be present. The crude dimer product may then be crystallized from a suitable solvent if desired, such as benzene, isopropanol or the like, and if desired may be further purified of residual [decachlorotetrahydro 4,7-methanoindeneone] ketonic C1oCl1o0 compound, by first dissolving it in a hot hydrocarbon solvent such as benzene and then precipitating it out of solution by the addition of a hydrocarbon-miscible non-solvent for the [dodecachlorotetrahydro-4,7-methanoindene] hexachlorocyclopentadene dimer, such as methanol, in which the y[decachlorotetrahydro-4,7-methanoindeneone] C1oCl1u0 ketone is soluble. The product may be'further purified if desired, by recrystallization from an aliphatic alcohol such as isopropanol. The resulting [dodecachlorotetrahydro 4,7 methanoindene] hexachlorocyclopentadiene dimer is a white, crystalline solid which sublimes without melting at temperatures above about 240 C., is appreciably'soluble in benzene, acetone, kerosene, carbon tetrachloride, etc. and while virtually insoluble in methanol, is appreciably soluble in the lower aliphatic alcohols having two or more carbon atoms, such as ethanol, isopropanol, etc., particularly at elevated temperatures.

The quantity of PCls'to be used in the preparation of the dimer is not critical, but for best yields should be at least the molecular equivalent of the [decachlorotetrahydro-4,7-methanoindeneone] ketonic CzaClmO com- In the drawings, [the single] Figure 1 illustrates the 65 pound, so as to furnish two chlorine atoms to replace the keto oxygen as indicated in the reaction above illustrated, and to react ywith any water of hydration present. Thus, although it is desirable to use [decachlorotetrahy- 3 dro-4,7-methanoindeneone] ketonic CroCIioO compound starting material in as low a state of hydration as possible, nevertheless, hydrated forms may be used if a sufficient quantity of PCls is employed to react with all the water of hydration as well as with the keto oxygen, forming POC13 and HC1, and when the expression equimolecular quantities is used in the claims to describe the proportions of reactants, it is to be understood to mean a quantity of PCls suicient to react with the keto oxygen and also with the water of hydration present. However, as the use of excesses of PCls are not only wasteful, but entail handling of the troublesome HC1 formed as a byproduct of the reaction of PCls with the water of hydration, it is preferable to dehydrate the [decachlorotetrahydro-4,7-methanoindeneone] ketonic CzoClroO compound as much as practicable before carrying out the reaction. In general, therefore, quantities of PCl5 only slightly in excess of the molecular equivalent of the [decachlorotetrahydro 4,7 e methanoindeneone] ketonic CzaClmO compound as dened are desirable.

The temperature to which the mixture of deca[chloro tetrahydro-4,7-methanoindeneone] CzoC'lzoO ketone and PCI5 is heated should be at least about 70 C., preferably between about 115 C. and about 160 C. The reaction is usually complete in a period of between about one hour and about six hours. The desired reaction product is separated from the resulting yoily reaction mixture, for example by cooling and drowning in an excess of water, for example between about 5 and about l0 volumes of water per volume of the oily reaction mixture, whereupon solid [dodecachlorotetrahydro-4,7methanoindene] hexa'- chlorocyclopenradiene dimer crystallizes and may be separated by suitable means such as filtration, etc. The resulting crude product is purified by washing with a solvent for [decachlorotetrahydro-4,7methanoindeneone] the ketonic CioClroO compound, for example methanol.

The hexachlorocyclopentadiene dimer prepared according to my invention, has the infrared spectrogram shown as dotted line A in [the] Figure 2. It is identical with the spectrogram of the dimer of hexachlorocyclopentadiene prepared by reacting hexachlorocyclopentadiene with aluminum chloride as described in I. Am. Chem. Soc. 71, page 954, March 1949, as indicated by the infrared spectrograrn of a material made by the AlCla condensation method which is shown as solid line B in [the] Figure 2.

The infrared spectrograms shown in the figures were prepared on a standard infrared recording spectrophotometer designed for measuring and recording the infrared transmission of solids, liquids and gases, comprising a double infrared beam which scans the spectrum through the wave length range ,2.0 to 16 microns, one part of the beam passing through the sample under study, the other passing through a compensating cell. If the sample under study absorbs radiation, the two beams become unequal. The magnitude of this inequality is a measure of the transmission of the sample of the particular wave length, and the record of these differences within the range of wave lengths scanned is the infrared spectrogram, recorded as an ink drawn line on a chart graduated in percent transmission as ordinates and in wave length as abscissae.

Solid samples, such as the compound of my invention, are conveniently measured in solution. The spectrogram shown in the gures was measured by dissolving 0.5 gram of the solid in carbon disulde and diluting to ml. with the solvent. A small amount of the solu-tion was then introduced into a liquid cell with sodium chloride windows and sealed. The cell was placed in the spectrophotometer in the path of one of the beams as described above.

The infrared spectr'ogram of any chemical compound serves as an accurate means for identifying the compound. It has been compared with a human fingerprint in its ability to identify a compound with, certainty` The characteristic reproducibility of the infrared spectrogram of a given compound is due to the facts that when a molecule is excited by infrared radiation it absorbs energy to a greater degree at some wavelengths than at others, and that the amount of absorption depends on the configuration and upon the linkages of the atoms composing the molecule. Accordingly, this spectrogram identities and characterizes the hexachlorocyclopentadiene dimer with certainty.

The following specific example further illustrates my invention.

EXAMPLE l Five parts of hydrated [decachlorotetrahydroflljmethanoindeneouel CzoClioO ketone, puried by Solution in methanol, precipitation with water and drying, were mixed with 2l parts of phosphorus pentachloride and the mixture heated for three hours at l25-l50 C. The resulting reaction mixture was cooled to 20 C. and drowned in water. The solid material which formed was filtered and Water washed, then Washed with methanol to dissolve any unreacted[decachlorotetrahydromethanoindeneone] CMCZIOO ketone which might be present, and dissolved in hot benzene. The benzene solution lwas mixed with a large excess of methanol to reprecipitate the product, which was filtered, dried and then recrystallized from isopropanol. Two parts of hexachlorocyclopentadiene dimer were obtained. An infrared spectrogram prepared from this product was found to correspond to that shown as broken line A in the figure and to be identical with the dimer of hexachlorocyclopentadiene prepared by reacting hexachlorocyclopentadiene with aluminum chloride as described in I. Am. Chem. Soc. 7l, page 954, March 1949, in physical properties as well as its infrared spectrogram, shown as solid line B in the figure.

While the above describes the preferred embodiments of my invention, it will be understood that departures may be made therefrom within the scope of the specification and claims.

kI claim:

l. A process for preparing [dodecachlorotetrahydro- 4,7-methanoindene] a l1exachloroeyclopentadiene dimer having the infrared spectrogrorn shown in Figure 2 of the drawings which comprises heating [decachlorotetrahydro- 4,7methanoindeneone'j4 the keronic CMCZNO compound having the infrared spectrogrom shown in Figure 1 of the drawings, with phosphorus pentachloride at temperatures between about 70 C. and about 160 C. for a period between about one hour and about six hours.

2. A process for preparing [dodecachlorotetrahydro- 4,7-methanoindene] a l1exochlorocyclopentodiene dimer having the infrared spectrogram shown in Figure 2 of the drawings which comprises mixing the ketonic CZOCZZOO compound having the infrared spectrogram shown in Figure 1 of the drawings, [decachlorotetrahydro-4,7rnethano indeneone] with a quantity of PCls at least the molecular equivalent of the said ketonie compound [decachlorotetrahydro-4,7-rnethanoindeneone1 and heating the resultant mixture to a temperature between about 70 C. and about C. for a period of between about o-ne hour and about six hours, cooling the resultant reaction mixture, drowning the mixture in water and recovering solid [dodecachlorotetrahydro-4,7-methanoindene] hexachlorocyclopentadiene dimer.

3. A process for preparing [dodecachlorotetrahydro 4,7-methanoindene] a kexucltlorocyclopentadiene dimer having the infrared spectrogrum shown in Figure 2 of the drawings which comprises mixing the substantially anhydrous [decachiorotetrahydro 4,7-methanoindeneone] ketonic CrnClroO compound having the infrared spectrogrum shown in Figure l of the drawings, with PCls and heating the resulting mixture to a temperature between about 70" C. and about 160 C. for a period of between about one hout and about six hours, cooling the resultant reaction mixture, drowning the mixture in water, re- References Cited in tpe le of this patent covering solid [dodecachlorotetrahydro-4,7-methanoin- 0r the Oflglal Patent dene] hexachlorocyclopentadiene dimer and purifying the Hunter et a1.: Juul- Am. @heul Soc', VOL 55, pages crude product by Washing it with methanol, dissolving 2557-70 (1933) it in benzene and drowning the benzene solution in 5 Degering et al.: An Outline of Organic Chemistry, methanol to precipitate the puried product and recoverthird edition, pages 56-7, 200 (1939).

ing the crystalline [dodecachlorotetrahydr0-4,7-methano- Chemical Abstracts, V01- 35, GQ11111111 2469 (1941)- indene] hexachlorocyclopentadene dimer. Abstract of article by Churbakov. 

